Polar electromagnetic relay



Dc- 20, 1950 P. w. TER BORG Erm. 2,965,733

PQLAR ELECTROMAGNETIC RELAY Filed Aug. 19, 1958 AGE g 2,965,733 Patented Dec. 2U, 1960 POLAR ELECTROMAGNETIC RELAY Petrus Wilhelmus Ter Borg, Friedrich Ludwig Jansen, and

Hendrik Johannes de Jong, all of Hilversum, Netherlands, assignors to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Filed Aug. 19, 1958, Ser. No. 755,907

Claims priority, application Netherlands Aug. 22, 1957 6 Claims. (Cl. 200-93) This invention relates to polar electromagnetic relays having a yoke of magnetizable material and an armature of similar material, the yoke being pre-magnetized by at least one permanent magnetic body of material having no electric conductivity and a high coercive field strength, which body is interposed between parts of the yoke. The permanent magnetic body interposed between parts of the yoke may in such relays consist, for example, of a material composed of substantially non cubic crystals of poly-oxides of iron and at least one of the metals barium, strontium, lead and possibly calcium. For such a material see United States Patents Nos. 2,762,777 and 2,762,778.

An object of the invention is to provide a polar relay having one or more permanent magnetic bodies of no electric conductivity, in which the non conductivity of these bodies is utilised to arrive at a simple and compact structure' which keeps the cost price low and more particularly may lead to relays of small size.

According to the invention, the armature and at least one part of the yoke, which is electrically separated from the other parts of the yoke by means of an interposed permanent magnetic body, have co-acting contact surfaces, the current being supplied to these contact surfaces through the armature and the relevant part of the yoke, respectively. In one preferred embodiment of the invention, the relay is designed as a bipolar relay, the armature of which is held alternately in either of its extreme positions by the pre-magnetization. In such a relay according to the invention, the armature is surrounded by an energizing coil and has one extremity pinched between two permanent magnetic bod.es magnetized in the same direction, to each of which adjoins a part of the yoke extending substantially in the direction of length of the armature, which parts of the yoke, located on difterent sides of the armature, at the level of the other extremity of the armature, have electric contact surfaces with which a contact surface of the armature alternately co-acts.

In a further preferred embodiment of the relay according to the invention, the armature is so designed that its magnetic reluctance is low and, for this purpose, the armature comprises a small strip of exible metal provided, at least on one side, with two rigid plates of magnetizable material extending in line in the direction of length of the strip` a portion of one plate which bends off the strip overlapping the adjacent end of the other plate, thus forming an airgap between these plates, which permits of a movement of one plate with respect to the other by ilexion of the part of the flexible strip located between the plates.

In order that the invention may be readily carried into effect, one embodiment will now be described in detail, by way of example, with reference to the accompanying drawing in which:

Fig. l is a longitudinal section, and

Fig. 2 is a plan view of an embodiment of the relay according to the invention in the form of a bipolar relay.

The relay shown has a yoke constituted by two parts 1 and 2 of the same shape, each constituted by a softiron strip. Each strip is rectangularly bent four times, so that its ends are located approximately in the same plane. Placed between the extremities 3 and 4 of the two strips are two non-conductive plates 5 and 6 of permanent magnetic material, which are magnetized in the same direction. A permanent magnetic material suitable for the plates S and 6 is composed of substantially non-cubic crystals of poly-ox.des of iron and at least one of the metals barium, strontium, lead and possibly calcium.

One extremity of the armature 7 of the relay is pinched between the plates 5 and 6. The armature comprises a thin strip of flexible metal 8, for example of Phosphor bronze, the pinched extremity of which and a further part have soldered to them, on each side, a thin softiron strip 9, 10 respectively.

The stacked parts of the yoke, the armature and the permanent magnetic bodies 5 and 6 are clamped together by means of a paper ribbon 20 tautly wound round this stack, which ribbon prior to winding was impregnated with a hardenable synthetic resin, for example a phenolformaldehyde resin. This resin is hardened after winding the ribbon 20 round the stack.

The free extremity of the armature, which extends between the ends 11 and 12 of the parts 1 and 2 of the yoke, is provided with two short soft-iron strips 13 and 14, which are secured, for example welded, to the exble strip only at the ends adjacent the pinched part of the armature. These ends of the strips 13 and 14 are overlapped with some play by upwardly-bent parts 15 and 16 of the soft-iron strips 9 and 10.

The armature 7 is surrounded by an energizing coil 17, the coil former 18 of which is maintained in position by the parts 1 and 2 of the yoke.

The extremities 11 and 12 of the parts 1 and 2 of the yoke are correctly spaced apart due to their being pressed into a small block 19 of insulating material, preferably of synthetic material having a high internal damping, such as polyester isocyanate. Due to their dovetail form (see Fig. 2), the extremities 11 and 12 are rigidly held in the block 19. The block 19 not only spaces apart the extremities of the parts 1 and 2 of the yoke, but also reduces any rebounce tendency of the contacts.

The extremities 11 and 12 of the parts 1 and 2 of the yoke are provided, on the side adjacent the armature, with slightly circular electric contact surfaces 21 and 22 obtained by depression of the yoke parts and with which the strips 13 and 14 of the armature 7 can co-operate. This is possible due to the thin metal strip 8 of the armature, between the areas where this strip is strengthened by the soft-iron strips 9, 10 and 13, 14 having a nonstrengthened part 23, which is readily flexible, thus permitting either the soft-iron strip 13 to engage the contact surface 21 or the soft-iron strip 14 to engage the contact surface Z2. In each of said positions, the armature is held by the pre-magnetization of the relevant part of the yoke provided by one of the permanent magnetic bodies 5 and 6.

The magnetic ux which passes in the direction of length through the armature 7 meets with low resistance in this armature due to the upwardly-bent parts 15 and 16 of the soft-iron strips 9 and llt) forming a comparatively narrow air-gap with the soft-iron strips 13 and 14.

The lower extremities of the parts 1 and 2 of the yoke and the armature 7, extending beyond the permanent magnetic bodies 5 and 6 are each connected to one of the lead-through pins 27 xed in the base '28 of a glass bulb 29 surrounding the relay. The base 28 also contains two lead-through pins which are electrically connected to an end of the energizing winding 17 such, for

example; asl).l Thepinsin'the base 28 are grouped so as to fit into the apertures of a tube'holder for a subminiature electron tube. The bulb 29, after the relay being mounted therein, may be evacuated, but it is alternatively possible to use a lling with a suitable gas, for instance an inert gas.

To ensure'satisfactory contact between the strips 13` and 14'of the armature and the contact surfaces Z1 and 22 of the free extremities of theparts-l and 2 ofthe yoke, these parts are preferably covered with a layer of noble metal, for example rhodium or silver.

The length a of the relay described Aby way of'example is' actually only about 4l mms., fromwhich it readily appears what small dimensions may be obtained with the portionsV of the yoke, a body of electrically insulating permanent magnet material interposed between `the por-I tions of the yoke and the armature, said armature being' positioned to engage an opposing surface portion of the yoke thereby making an electrical connection betweenthe armature and one of the opposing spaced portions of the yoke, and terminal means connected to said armature and said spaced opposing portions of the yokeforcomaA pletlng an electrical connection through said armature and said yoke.

2. A polarized relay comprising a yoke including two opposing portions each of a magnetizable electricallyconductive material, an karmature of magnetizable material resiliently mounted between the opposing spaced portions of the yoke, an energizing coilsurrounding a portion of the armature, two bodies of electrically insulating permanent magnet material clamping the armature between and separating the armature from the portions of the yoke, each of. said bodies being magnetized in the same direction, said armature being-positioned to alternately engage opposing surface portions of the yoke thereby making an electrical connection betweenthe armature'andone ol?l the opposing spaced portions of the yoke, and terminal means connected to said armature and said spaced opposing portions of the-yoke for completingan electrical connection through said armatureand said yoke."

3. A polarized relay comprising a yoke including two opposing portions each ofY ammagnetizable. electrically.

conductive material, an armature resiliently mounted between said portions of said yoke and comprising a thin ilexible metal strip, two rigid plates of magnetizable material extending in the direction of length of said strip, a portion of one plate bendng ol the strip and overlapping the adjacent extremity of the other plate therebyf'forming an air-gap between said plates which allows movement of4 one plate with respect to the other by flexion ofv the portion of thestrip betweenithe plates, an energizingv coil surroun'dingfa portion of thearmature, two bodies1of electricallyinsulatlng. permanent magnet material clamping the armature between andseparating thearmature from th'eportions oftheyoke, each of said bodiesbeing magnetized in the same direction, said armature being positioned to engage an opposing surface portion of the yoke thereby making an electrical connection between the armaturev and one of the opposing spaced portions .of

the yoke,l and terminal means connected to said armature:

and said spaced opposing portions off the yoke forl completingan electrical connection through said armature and said yoke.

4. A polar relay as claimedin claim .3,.inwhichfthe two parts of the yoke extend beyond'the contact surfacesof the armature and are ixedv in a'small block olinsulating material transverseY to theV direction of lengthv of-theV armature.

5. A polar relayv as claimedin clainr2, in` which-the assembly-comprising the partof thearmature1clamped=y between the permanent magnetic bodies, said bodies-fand the'adjoining parts ofthe yoke-are-clamped together with a ribbon of insulating material woundaround said-'partsl of theV yoke, Y said ribbonY being impregnated 'i with' aA the energizingl coil, the armature andthose partsof the` yoke which carry an electric contact surface.v

References VCited -in the le of this patent UNITED STATES PATENTS 2,473,353 Aust June'14,- 1949 2,677,027 Woods Apr. 27, 1954- 2,734,962 Cook Feb. 14,1956'- 2,848,579 Russell Aug: 193 1958'7 

